An open trial of levetiracetam for segmental and generalized dystonia

The neurobiological basis for novel experimental therapeutics in dystonia

Dystonia is a movement disorder characterized by involuntary muscle contractions, twisting movements, and abnormal postures that may affect one or multiple body regions. Dystonia is the third most common movement disorder after Parkinson's disease and essential tremor. Despite its relative frequency, small molecule therapeutics for dystonia are limited. Development of new therapeutics is further hampered by the heterogeneity of both clinical symptoms and etiologies in dystonia. Recent advances in both animal and cell-based models have helped clarify divergent etiologies in dystonia and have facilitated the identification of new therapeutic targets. Advances in medicinal chemistry have also made available novel compounds for testing in biochemical, physiological, and behavioral models of dystonia. Here, we briefly review motor circuit anatomy and the anatomical and functional abnormalities in dystonia. We then discuss recently identified therapeutic targets in dystonia based on recent preclinical animal studies and clinical trials investigating novel therapeutics.

Update on current and emerging therapies for dystonia

Treatment strategies for dystonia depend on the focal, segmental or generalized distribution of symptoms. Chemodenervation with botulinum toxin remains the treatment of choice for focal- or select-body regions in generalized and segmental dystonia. A potentially longer acting formulation of botulinum toxin is being investigated besides the currently available formulations. Electromyography increases toxin injection accuracy and may reduce injection number, frequency, side effects and costs by identifying dystonic muscle activity. Oral anticholinergics, baclofen and clonazepam are used off-label, but novel drugs in development include sodium oxybate, zonisamide and perampanel. Characterizing dystonia as a sensorimotor circuit disorder has prompted the use of noninvasive neuromodulation procedures. These techniques need further study but simultaneous rehabilitation techniques appear to also improve outcomes. Pallidal deep-brain stimulation is beneficial for medication-refractory primary generalized and possibly focal dystonia such as cervical dystonia. Certain genetic conditions are amenable to specific therapies and future gene-targeted therapies could benefit selected dystonia patients.

[New medications for dystonia]

Although there are some newly-developed options to treat dystonia, its medical treatment is not always satisfactory. Zolpidem, an imidazopyridine agonist with a high affinity to benzodiazepine receptor subtype ω1, has been reported to improve clinical symptoms of dystonia in some cases. We conducted an open-label study to assess the efficacy of zolpidem in 34 patients with primary dystonia patients, The Burke Fahn Marsden Dystonia Rating Scale (BFMDRS) scores in the patients were decreased from 7.2 ± 7.9 to 5.5 ± 5.0 after zolpidem therapy (P=0.042). Next we evaluated 55 patients with primary and secondary dystonia, 16 of 55 patients (29%) responded to zolpidem, and secondary dystonia, particularly post-traumatic dystonia, was more responsive than primary dystonia (5 of 11 [46%] vs 11 of 44 [25%]). The efficacy of zolpidem was comparable to that of other oral medications in our previous study; 33 of 89 dystonia patients (37%) responded to trihexyphenidil, 13 of 53 (25%) responded to clonazepam, and 4 of 21 (19%) responded to baclofen. In conclusion, our large scale study suggested that zolpidem may be a therapeutic option for dystonia, particularly post-traumatic dystonia.

Current and future medical treatment in primary dystonia

Dystonia is a hyperkinetic movement disorder, characterized by involuntary and sustained contractions of opposing muscles causing twisting movements and abnormal postures. It is often a disabling disorder that has a significant impact on physical and psychosocial wellbeing. The medical therapeutic armamentarium used in practice is quite extensive, but for many of these interventions formal proof of efficacy is lacking. Exceptions are the use of botulinum toxin in patients with cervical dystonia, some forms of cranial dystonia (in particular, blepharospasm) and writer's cramp; deep brain stimulation of the pallidum in generalized and segmental dystonia; and high-dose trihexyphenidyl in young patients with segmental and generalized dystonia. In order to move this field forward, we not only need better trials that examine the effect of current treatment interventions, but also a further understanding of the pathophysiology of dystonia as a first step to design and test new therapies that are targeted at the underlying biologic and neurophysiologic mechanisms.

A randomized, double-blind, placebo-controlled trial of levetiracetam for dyskinesia in Parkinson's disease

BACKGROUND

This randomized double blind, placebo-controlled crossover study investigated the antidyskinetic effects of levetiracetam in Parkinson's disease.

METHODS

Sixteen participants with levodopa-induced dyskinesia were enrolled. Hourly videotaped dyskinesia assessments scored by the Goetz method and hourly Unified Parkinson's Disease Rating Scale motor subscale scoring were conducted on 1 day at the end of each treatment period.

RESULTS

Dyskinesia was slightly less on placebo (P = .26). Patient diary records also showed less dyskinesia on placebo (P = .10). Parkinsonism was a little worse on levetiracetam, at borderline statistical significance (P = .05).

CONCLUSIONS

Levetiracetam was well tolerated at doses up to 2000 mg per day, but we did not detect any antidyskinetic properties.

Therapeutic challenges in dystonia

Because dystonia can vary in clinical presentation and etiology, proper diagnosis and classification of these disorders are important in making therapeutic decisions. In primary dystonia, treatment is generally geared toward alleviating symptoms rather than curing the underlying condition, therefore severity of contractions, pain, and functional and social impact are also factors to consider in determining if and how to initiate therapy. On the other hand, if a secondary cause is identified, then it is often appropriate to direct treatment toward the underlying disorder. Treatment options include physical and occupational therapy, oral medications, botulinum toxin, and surgery. This article briefly reviews the clinical features, pathophysiology, and classification of dystonia before reviewing current therapeutic options.

Levetiracetam for managing neurologic and psychiatric disorders

PURPOSE

The role of levetiracetam in different epileptic, nonepileptic, neurologic, and psychiatric disorders is discussed.

SUMMARY

Levetiracetam, an antiepileptic drug (AED), was first approved as an adjunctive therapy for the treatment of partial epilepsy in adults. It is currently being used in the treatment of multiple seizure disorders, including generalized tonic-clonic; absence; myoclonic, especially juvenile myoclonic; Lennox-Gastaut syndrome; and refractory epilepsy in children and adults. Data are emerging on possible uses of levetiracetam outside the realm of epilepsy because of its unique mechanisms of action. There is preliminary evidence about the efficacy of levetiracetam in the treatment of different psychiatric disorders, including anxiety, panic, stress, mood and bipolar, autism, and Tourette's syndrome. The most serious adverse effects associated with levetiracetam use are behavioral in nature and might be more common in patients with a history of psychiatric and neurobehavioral problems.

CONCLUSION

Levetiracetam is an effective AED with potential benefits in other neurologic and psychiatric disorders. The benefit-risk ratio in an individual patient with a specific condition should be used to determine its optimal use. Levetiracetam's use in nonepileptic conditions is not recommended until more data become available from larger trials.

Brivaracetam and seletracetam, two new SV2A ligands, improve paroxysmal dystonia in the dt sz mutant hamster

Previous examinations demonstrated antidystonic effects of the synaptic vesicle protein 2A (SV2A) ligand levetiracetam in the dt(sz) mutant hamster, an animal model of paroxysmal non-kinesiogenic dyskinesia in which dystonic episodes can be induced by stress. In the present study, we examined the effects of the two new, high affinity SV2A ligands, brivaracetam and seletracetam, in comparison to levetiracetam on the severity of dystonia in mutant hamsters. Seletracetam (50 and 75 mg/kg i.p.) and brivaracetam (75 mg/kg i.p.) reduced the severity of dystonia to a comparable extent as levetiracetam (50 and 75 mg/kg i.p.). These data confirm the therapeutic potential of these pyrrolidone derivatives for the treatment of paroxysmal dystonia.